1. Field of the Invention
The invention relate to an image guided surgery system.
2. Description of Related Art
Such an image-guided surgery system is known from the U.S. Pat. No. 5,389,101.
An image-guided surgery system is used to show a surgeon the position of a surgical instrument in an operating zone in the body of the patient during surgery. The known image-guided surgery system comprises a position measuring system for measuring the position of the surgical instrument. Prior to surgery, images (for example, CT or MRI images) are made of the patient. During surgery the position measuring system measures the position of the surical instrument relative to the patient. The image guided surgery system is provided with a computer which calculates the position in such a pre-recorded image which corresponds to the measured position of the surgical instrument. The pre-recorded image is displayed on a monitor and the actual position of the surgical instrument is indicated therein. The surgeon can see where the surgical instrument is situated in the operating zone by observing the image displayed on the monitor, without the surgeon having a direct view thereof. The image on the monitor reveals how the surgeon can move the surgical instrument in the operating one without a serious risk of unnecessarily damaging tissues and notably without a risk of damaging vital organs.
An image-guided surgery system of this kind is preferably used in neurosurgery for showing the surgeon exactly where the surgical instrument is situated in the brain during cerebral surgery.
The position measuring system measures the position of the surgical instrument by recording ages of the surgical instrument from different directions by means of two cameras. The position measuring system also measures the position of the patient. Thus, the cameras supply image signals that represent the position of the surgical instrument and the position of the patient. The data processor derives the position of the surgical instrument relative to the patient during surgery from image signals from the individual cameras and from the positions of the cameras relative to one another.
Often, the surgical instrument is an endoscope. The term endoscope is used hereinafter to designate a surgical instrument that is suitable to be entered into the body of a patient to be examined and which provides visual information, e.g. in the form of an image or a view, of the interior of patient's anatomy. During surgery, it may occur that the endoscope cannot function properly, in particular because it cannot supply appropriate visual information.